A significant influx of moisture and heat will be intercepted by a strong short wave tonight diving southeast out of Minnesota. The end result will be strong to severe thunderstorms. Initiation will take place in Minnesota towards late afternoon and then the storms will sweep southeast towards Iowa, SW Wisconsin, and NW Illinois. The Storm Prediction Center has upgraded the risk from slight to enhanced across much of my area.
While a small tornado threat may develop as storms fire in Minnesota, the initial concern appears to be large hail. As the storms grow upscale high wind will become a greater concern. In fact, an MCS is quite likely that needs to be watched for damaging winds and heavy rain late into the night as it propagates southeast across eastern Iowa and NW Illinois.
Here is the forecast CAPE at 7:00pm this evening. Increasingly unstable air is evident along with steep lapse rates in the source region of development. Storms will ride this southeast.
This is a simulated radar from the 3K NAM at 11:00PM tonight as the squall line punches into Iowa and Wisconsin from Minnesota.
The GFS shows this for rainfall through 7:00AM Monday.
Just to emphasis, this appears to be a very late evening or overnight event for my area as storms impact Minnesota first on their journey southward. Watches will be issued for some later today or tonight as the event unfolds. Roll weather...TS